Prior art optical fiber lateral scanners of the type are known to comprise a stationary part, including a bearing support and an electromagnet, and a moving part including a permanent magnet attached to an optical fiber (see, e.g., U.S. Pat. No. 3,470,320; U.S. Pat. No. 5,317,148). In these devices, the optical fiber is anchored at one end to a bearing support and serves as a flexible cantilever, whereas the free end of the optical fiber is arranged such, that it can move in the direction perpendicular to its own axis. The permanent magnet is placed in a gap between the poles of the electromagnet.
A prior art optical fiber lateral scanner according to U.S. Pat. No. 4,236,784 also comprises a stationary part, which includes a bearing support and an electromagnet, and a moving part, including a permanent magnet. In this device, the permanent magnet is made as a thin film of magnetic material coated onto the optical fiber, whereas the electromagnet is arranged as an array of thin-film conductors on a substrate layer that is placed orthogonal relative to the end face of the optical fiber.
Another optical fiber lateral scanner comprising a stationary part and a moving part is known from U.S. Pat. No. 3,941,927. The stationary part comprises a bearing support and a permanent magnet, whereas the moving part includes a current conductor arranged as a conductive coating on the optical fiber. The optical fiber is placed in a gap between the pole pieces of the permanent magnet and fixedly attached to the bearing support, so that its free end can move in the direction approximately perpendicular to its own axis, and serves as a flexible cantilever. The current conductor is connected with a source of control current.
A disadvantage of above described optical fiber lateral scanners is that they do not allow for performance data necessary to be incorporated in a miniature optical fiber probe used in an OCT apparatus, in particular, miniature size, combined with required deflection of the optical fiber.
U.S. Pat. No. 6,608,684 (RU Pat. No. 2,148,378) describes an optical fiber lateral scanner, which is part of a miniature optical fiber probe. The design of the optical fiber lateral scanner is optimized for obtaining maximum deflection of the optical fiber with limited scanner size. This scanner comprises a stationary part and a moving part. The stationary part includes a bearing support and a magnetic system, said magnetic system comprising a first permanent magnet. The moving part includes a movable current conductor and an optical fiber rigidly fastened to the current conductor. The optical fiber serves as a flexible cantilever and is fixedly attached to the bearing support with a capability for a distal part of said optical fiber of being deflected in a direction substantially perpendicular to its own axis. The current conductor is made as at least one loop, which envelopes the first permanent magnet in the area of one of its poles. In a particular embodiment the first permanent magnet is provided with a groove extending in a direction substantially parallel to the axis of the optical fiber, the optical fiber being placed into said groove. In another embodiment the magnetic system additionally comprises a second permanent magnet, with one pole facing the analogous pole of the first permanent magnet, which is enveloped by the current conductor. In a different embodiment the permanent magnets are aligned at their analogous poles, whereas the optical fiber is placed into a through-hole extending therethrough in a direction substantially parallel to the axis of the optical fiber, the through-hole being formed by the facing grooves made in the analogous poles of the permanent magnets.
However, limitation common to both the optical fiber lateral scanner and the miniature optical fiber probe referred to in U.S. Pat. No. 6,608,684 regards the complexity for manufacturing due to the fact that the design is very critical to the shape and dimensional tolerances of scanner elements and assembly. In particular, placing the coil around the magnet inside the probe body is very difficult and some critical bonding places are extremely hard to access.